North Korea and its recent anti-American stamps have created quite the stir in the media. Scott catalog new-issues editor Marty Frankevicz explores this phenomenon and offers some much-needed philatelic perspective.

Anyone who collects United States stamped envelopes understands that one of the most difficult tasks facing the collector is to identify die types.

Dies are used to print an embossed stamp, known as a stamped indicium, onto a U.S. stamped envelope. Three dies — the master die, the hub die, and the working die — are used in the printing process. On the master die, lines that will remain colorless are cut into the end of a soft steel cylinder.

The image on the master die is a negative, mirror image. Because the master die will wear quickly if it is used to print the stamped indicium, a working die must be created.

An intermediate die, known as the hub die, is created to transfer the image from the master die to the working die. The image on the hub die is a positive image of the final design of the stamped indicium. The hub die is used to create the working die, which, again, is a negative, mirror image, a replica of the master die.

The working die is used to print the embossed stamped indicium on the envelope paper with the help of a resilient platen. The platen is hard enough to produce a clear impression from the raised parts of the die and flexible enough to push the paper into the uninked recesses, creating raised images and lettering.

After much use, working dies were worn smooth and were sometimes recut, resulting in changes in die characteristics and varieties.

The new fourth edition of the Catalog of the 20th and 21st Century Stamped Envelopes and Wrappers of the United States, published by the United Postal Stationery Society, offers far greater detail of stamped envelope production.

The book features easy-to-use charts and step-by-step instructions for identifying dies. The catalog uses envelope sizes and shapes to help collectors sort envelopes before they begin to identify the die types.

The new 432-page, full-color catalog, edited by Dan Undersander, includes listings of all U.S. stamped envelopes, letter sheets, and wrappers identified by UPSS numbers and Scott catalog numbers. More than 600 value changes have been made to the listings.

New illustrations showing air letter inscriptions and overlay varieties have been added. More than 150 new postal stationery items have been added, including new issues through December 2016.

For collectors of stamped envelopes, letter sheets, or wrappers, this catalog is an essential book. The hardbound book is priced at $52 for UPSS members and at $65 for nonmembers, including shipping to domestic addresses. To order, visit the UPSS website or email the publications office.